Komatiites
Fig.1: Variations in texture across a several metre-thick komatiite flow, showing well developed layering. Modified from Dostal, J. (2008).See more on alexstrekeisen.it
Archean komatiite volcanism controlled by the evolution of …
In this study, we provide the first evidence of a fundamental relationship between the spatiotemporal variation in komatiite abundance, geochemistry, and volcanology and the …
اقرأ أكثر
(PDF) Komatiites
Komatiites are conventionally considered to be derived from high temperature melts that have eruption temperatures of about 1600°C and are produced by high degrees of anhydrous melting of mantle ...
اقرأ أكثر
HSE and Re-Os systematics of the 3.3 Ga Weltevreden …
I. Weltevreden Formation komatiites formed approximately 3.3 billion years ago. II. By 3.3 Ga, the terrestrial mantle had absolute and relative HSE abundances similar to those in the modern mantle. III. Weltevreden komatiites formed via anhydrous and high degree, high temperature partial melting, likely in a mantle plume source. II.
اقرأ أكثر
From the mantle source to the crustal sink: magmatic
Paleoproterozoic (2.05 Ga) komatiites are widespread in the Central Lapland Greenstone Belt (CLGB), northern Finland. Close association with sulfur (S)-rich country rocks and spatiotemporal connection with the Cu-Ni(-PGE) deposits of Kevitsa and Sakatti make these komatiites interesting targets for sulfide deposit exploration. We provide whole-rock …
اقرأ أكثر
Insights into early Earth from the Pt–Re–Os isotope and …
Komatiites of the Barberton Greenstone Belt (BGB) in South Africa, ... and crushed in an alumina-faced jaw crusher. A 200-g aliquot of crushed sample was pre-ground in an alumina shatter box, then ground to a fine powder in an alumina-faced disk mill and used for the geochemical studies. The remaining crushes of the largest available and ...
اقرأ أكثر
Lithogeochemistry and origin of the komatiites from …
The komatiites are variously affected by carbonate alteration and deformation and the rhyolitic rocks are mostly strongly silicified. The komatiites are of the Al-undepleted type, with a MgO content of 25–45 wt %, while the mafic intrusions are tholeiitic in character, varying from gabbronorite to diorite in composition.
اقرأ أكثر
sbm mining gold quartz rock in komatiites crusher for …
Open sidebar. changjiangsx; sbm; Repository
اقرأ أكثر
Platinum group element geochemistry of komatiites from …
The remaining parts of the quarters were polished on all sides using SiC sand paper to remove drill bit or saw marks, washed in deionized water, dried, and crushed in an alumina-faced jaw crusher. A 100- to 150-g aliquot of crushed sample was ground in an alumina shatter box and finely reground in an alumina-faced disk mill, and was used for ...
اقرأ أكثر
(PDF) Volcanological and petrogenetic characteristics of komatiites …
The Saw Mill Complex (SMC) is a 1 275 m thick layered komatiitic sequence in the 3.3 Ga Weltevreden Formation, uppermost stratigraphic unit of the Onverwacht Group in the northern part of the Barberton Greenstone Belt, South Africa. A series of
اقرأ أكثر
Geochemistry of a komatiitic, boninitic, and tholeiitic basalt
Samples were crushed with a steel jaw crusher at the University of Western Australia to a size of 0.2–2 ... komatiites, tholeiitic basalts, and boninites. Komatiites have been subdivided into Al-undepleted (AUK, or Munro-type) and Al-depleted (ADK, or Barberton-type) varieties, and ADK into Al-depleted and Al-depleted–Ti-enriched subtypes ...
اقرأ أكثر
In situ determination of Os, Ir, and Ru in chromites formed …
For whole-rock analyses, the chromitite samples were crushed in a steel jaw crusher and then pulverised in a W-carbide shatterbox for 3 ... Komatiites are richer in IPGE than all other magmas. This probably reflects the fact that komatiites formed by very high degrees of partial melting, sufficient to dissolve all the sulphides in the mantle ...
اقرأ أكثر
Highly siderophile element systematics of the 3.3 Ga …
Komatiites are particularly useful for determining absolute and relative abundances of the highly siderophile elements (HSE, including Os, Ir, Ru, Pt, Pd, and Re) in their mantle sources. ... and crushed in an alumina-faced jaw crusher. A 100-g aliquot of crushed sample was ground in an alumina shatter box and re-ground in an alumina-faced disk ...
اقرأ أكثر
Arndt, N., Lesher, C. M. & Barnes, S. J. 2008.
Komatiites often have exquisite disequilibrium mineral textures seldom seen in younger rocks. These spinifex textures give komatiite a mystical aura, keenly sought after, …
اقرأ أكثر
(PDF) Komatiites: their geochemistry and origins
Komatiites are ultra-hot ultramafic lavas, largely restricted to the Archaean. They represent an extreme endmember of terrestrial magmatism and challenge our understanding of …
اقرأ أكثر
The discovery and petrogenetic significance of komatiites
Komatiites are also important to the mining economy as some host major nickel deposits. The field exposures of komatiites in the Onverwacht Group in the Barberton Mountain Land are encompassed as a world geoheritage site and sampling is restricted. Since their discovery there have been hundreds of academic publications on komatiites from ...
اقرأ أكثر
Highly siderophile element systematics of the 3.3 Ga …
Komatiites are ultramafic volcanic rocks that occur mainly in Archean and Paleoproterozoic greenstone belts. These olivine-rich rocks are assumed to have crystallized from magmas that have about 28–30 wt % MgO. ... and crushed in an alumina-faced jaw crusher. A 100-g aliquot of crushed sample was ground in an alumina shatter box and re-ground ...
اقرأ أكثر
Platinum group element geochemistry of komatiites from …
It should be also taken into account that, although most models for the generation of komatiites involve hot melting of dry peridotite (e.g., Arndt, 1976; Herzberg and O'Hara, 1985; Herzberg and Zhang, 1996), some authors have suggested derivation of komatiites by hydrous melting in island arcs (e.g., Allègre, 1982; Parman et al., 1997 ...
اقرأ أكثر
(PDF) Komatiites
Komatiites are ultramafic volcanic rocks that occur mainly in Archean and Paleoproterozoic greenstone belts. These olivine-rich rocks are assumed to have crystallized from magmas that have...
اقرأ أكثر
Arndt, N., Lesher, C. M. & Barnes, S. J. 2008.
Komatiites are igneous rocks mainly of Archaean age. Their ultramafic origin is controversial and has been attributed to either high degrees of dry melting of peridotite in deep mantle plumes at temperatures up to 500°C hotter than today, or to melting at shallow depth, in volatile-rich (hydrous) mantle with temperatures not much different than the 1200–1500°C (for …
اقرأ أكثر
Archean komatiite volcanism controlled by the evolution of …
The komatiites of the Southern Cross greenstone belt form an intermediate group between the intracontinent (low-MgO, unchannelized) and the continent edge (high-MgO, channelized) type komatiites. These magmas have high-MgO contents ( 18 ), but are unchannelized, cumulate-poor, and unmineralized ( 18 ).
اقرأ أكثر
Komatiite
Les komatiites contiennent des olivines spinifex (minéraux en forme de baguettes), témoins d'une cristallisation extrêmement rapide. Affleurements et répartitions dans le temps Sur Terre, les komatiites sont très rares et essentiellement limités aux roches d'âge archéen.
اقرأ أكثر
Komatiite
Komatiites erupted billions of years ago as pulsating streams of white-hot lava. Their unusual chemical compositions and exceptionally high formation temperatures produced highly fluid lava that crystallized as spectacular layered flows. Investigation of the extreme conditions in which komatiites formed provides important evidence about the ...
اقرأ أكثر
Contrasting komatiite belts, associated Ni–Cu–(PGE) …
komatiites and hence promoting ore genesis (Lesher et al. 2001). However, this study questions the role of crustal ... a ceramic-faced jaw crusher. A 100–150 g aliquot of crushed sample was ground in an agate mill and was used for geochemical studies. Figure 2 (a) Simplified geological map of the Mt Keith domain, showing the location of the ...
اقرأ أكثر
(PDF) Lithophile and siderophile element systematics of …
Geochemical diversity in oceanic komatiites and basalts from the late Archean Wawa greenstone belts, Superior Province, Canada: trace element and Nd isotope evidence for a heterogeneous mantle. Derek Wyman. Precambrian Research, 1999. download Download free …
اقرأ أكثر
Geochemical constraints on komatiite volcanism from Sargur …
The komatiites are divided into three groups based on total REE, shape of the patterns and Eu anomalies. Group I komatiites are characterized by low to moderate total REE (8.77–22.26 ppm) and show flat REE patterns with (Gd/Yb) N ratios (0.62–1.42) except few samples which show either slight depletion or enrichment in MREE (Fig. 16 a).
اقرأ أكثر
Komatiites and Ni-Cu-PGE deposits
Komatiites are exclusive ancient rock types which exhibit a unique spinifex texture. The Ni-Cu-PGE mineralisation generally occurs as massive sulfide ore at the floor of the komatiitic flow or as disseminated sulfides through olivine-rich layers. It is worth noting that the critical features whether the mineralisation will occur are the flow ...
اقرأ أكثر
Komatiite-associated Ni–Cu–PGE deposits (by C. M. Lesher …
Komatiite - July 2008. Introduction. There are two main types of ore deposits associated with komatiites: primary magmatic sulfide deposits, mined chiefly for their nickel content with minor by-product Cu and PGEs, and secondary laterite deposits enriched in nickel and cobalt, developed over thick olivine cumulate units, the latter known thus far only in the Yilgarn Craton of Western …
اقرأ أكثر
Late-Paleoarchean Ultra-Depleted Commondale Komatiites: …
Komatiites provide insight into Archaean mantle sources and surface processes that were not present in later stages of Earth's evolution. They were generated and erupted at very …
اقرأ أكثر
Contrasting komatiite belts, associated Ni–Cu–(PGE) …
komatiites is metasomatic introduction or depletion of elements during metamorphic and/or hydrothermal fluid–rock interaction. In the Agnew–Wiluna greenstone belt, some portions of …
اقرأ أكثر
A Fractional Crystallization Link between Komatiites, Basalts, …
samples were first coarsely crushed in a steel jaw crusher, then powdered using ceramic ball milling equipment during initial characterisation of the Winnipegosis Komatiite Belt (Hulbert et al ...
اقرأ أكثر